1. Field of the Invention
The present invention relates to an apparatus for gluing a polarization plate to a surface of a liquid crystal cell in a manufacturing process of a liquid crystal panel.
2. Description of the Prior Art
There is a process in the manufacturing of a liquid crystal panel where a polarization plate is glued to a liquid crystal cell (liquid crystal display element).
Some of the principal functions required for the gluing apparatus in the manufacturing process of the liquid crystal panel include the functions of:
gluing the polarization plate to the liquid crystal cell with accuracy; PA1 cleaning the surface of the liquid crystal cell before the polarization plate is glued thereto; PA1 automatizing the gluing process for higher productivity at a good yield rate. PA1 a feeding mechanism for feeding as long as a predetermined length a strip-shaped material overlapped by a polarization plate and a carrier tape; PA1 a half-cutting mechanism for cutting only the polarization plate of the strip-shaped material; PA1 a glue head for absorbing the polarization plate cut by the half-cutting mechanism to feed the same to the surface of the liquid crystal cell; PA1 a retracting mechanism for retracting the strip-shaped material in a state where the polarization plate is absorbed and supported by the glue head; and PA1 a winding mechanism for winding only the carrier tape after the polarization plate is removed, and, PA1 a plate for being pushed to the surface of the liquid crystal cell to relatively move against the surface of the liquid crystal cell; PA1 a hood for covering space around the plate; PA1 an absorption apparatus for absorbing air within the hood.
A gluing apparatus for polarization plate as a prior art is disclosed, where a tape-shaped polarization plate material is cut according as a predetermined length and this polarization plate chip is automatically glued to the surface of the liquid crystall cell.
However, there is a problem in the conventional gluing apparatus in that, although a gluing time is short per polarization plate chip, a glued position is not accurate, and, although the accuracy of the glued position is acceptable, the gluing time per chip is lengthened to thereby decrease the productivity, and no function is provided for removing foreign objects from the surface of the liquid crystal cell before the gluing process, thereby reducing the yield rate.
The thing is that there has been disclosed no gluing apparatus satisfying the required needs thus described.
FIG. 8 relates to a conventional gluing apparatus for a polarization plate, and more particalarly to side views for illustrating process where a cut polarization plate chip is taken from a carrier tape to be transported to a liquid crystal cell.
In FIG. 8A, a polarization plate material 12 is a strip-shaped material glued to a carrier tape 10, where only an upper side polarization plate material 12 is cut by a half-cutting instrument to thereby be divided into respective polarization chips 14 and sequentially transported from left to right direction.
When a forefront polarization plate chip 13 comes to a predetermined position, a glue head 16 is moved from a reference position 18 to left direction to thereby come to an upper portion of the polarization plate chip
In FIGS. 8B through 8E, the reference position 18 of the glued head 16 is illustrated in an alternate long and short dash line.
Next, as illustrated in FIG. 8C, the glue head 16 is lowered to vacuum-suck the polarization plate chip 14, and as illustrated in FIG. 8D, a strip-shaped material of as much as one polarization plate chip is transported to the right direction under the same vacuum-sucked state, and the glue head 16 is synchronized there with to thereby be transported to the right direction in the same distance as the strip-shaped material.
Next, as illustrated in FIG. 8E, only the glue head 16 is moved to the right direction again even after stoppage of the strip-shaped material in order to prevent interference between mechanisms and to take off bond of adhesives between the polarization plate material and the carrier tape.
Now, bond by the adhesives between the polarization plate chip 14 and the carrier tape 10 is taken off to thereby allow the polarization plate chip 14 to be separated from the carrier tape 10.
Then, as illustrated in FIG. 8F, the glue head 16 is raised up to return to the reference position.
Next, the glue head 16 proceeds in a vertical direction from surface and moves to direction of the liquid crystal cell, and then the polarization plate chip 14 is glued to the liquid crystal cell by a release operation thereof to thereby cause the glue head 16 to return to the reference position. By this, the glue head 16 returns to a state of FIG. 8A.
The polarization plate chip is sequentially glued to the liquid crystal cell by repeated operations thus described.
Furthermore, there have been disclosed a few known means to remove foreign objects from the surface of the liquid crystal cell.
By way of example, the surface of the liquid crystal cell is cleaned with a glued roller, or air is pumped thereon or a rotary brush is used.
FIG. 9 is a perspective view for illustrating a conventional example where a cleaning plate is used.
Accordingly to FIG. 9, a liquid crystal cell 20 is put on an up-down stage and an edge 23 of a plate 22 is placed parallel lengthwise to the rectangular liquid crystal cell 20, and the plate 22 is moved verically to lengthwise direction of the liquid crystal cell 20. By this, the edge 23 of the plate 22 removes the foreign objects on the surface of the liquid crystal cell 20.
However, there is a problem in the conventional process illustrated in FIG. 8 in that moving processes of the glue head are numbered too many, and time (cycle time) required for gluing one polarization plate chip to the liquid crystal cell is lengthened.
In other words, there are six processes needed for the glue head in FIG. 8, i.e., move to left, lower suction, right synchronized move, right single move, rise and gluing operations.
Furthermore, in a conventional cleaning apparatus illustrated in FIG. 9, the liquid crystal cell 20 on the stage is raised up to a predetermined position and stopped thereat, and by this, contact between the surface of the liquid crystal cell 20 and the plate 22 is realized.
Accordingly, when thickness of the liquid crystal cell 20 is changed, contact pressure thereof is changed to a great extent.
Furthermore, the length where the edge 23 of the plate 22 contacts the liquid crystal cell at one time is relatively long because a lengthwise dimension of the rectangular liquid crystal cell 20 is the same as the contacted length.
Accordingly, there is another problem in that the cleaning cannot be performed uniformly because it can be affected by rectilinear accuracy of the edge 23 at the plate 22 or by ruggedness of the surface 21 of the liquid crystal cell 20.